Movement bahaviour of three South African inshore sparid species in rocky intertidal and shallow subtidal habitats
- Authors: Watt-Pringle, Peter Andrew
- Date: 2009
- Subjects: Sparidae -- South Africa , Diplodus , Sparodon Durbanensis , Fisheries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5302 , http://hdl.handle.net/10962/d1005147 , Sparidae -- South Africa , Diplodus , Sparodon Durbanensis , Fisheries -- South Africa
- Description: This study investigated the movement behaviour of three inshore South African sparids – blacktail (Diplodus sargus capensis), zebra (Diplodus cervinus hottentotus) and white musselcracker (Sparodon durbanensis), popular inshore fishery species caught in appreciable numbers along much of the South African coast. The first study component examined movements of juveniles in a rocky intertidal nursery area at Schoenmakerskop near Port Elizabeth. Juveniles in a single gully were tagged with Visible Implant Elastomer (VIE) and resighted at the study site on snorkelling gear over a seven-month period. Tagged zebra and musselcracker displayed limited movement between potential low tide refuges, being observed repeatedly in the same gully over the full duration of the study. However, blacktail displayed greater movements and were seen infrequently in the later period of the study, probably having undergone an ontogenetic habitat shift to subtidal areas. There was evidence that blacktail maintain use of their intertidal nursery over high tide, during which the other two species moved into shallower areas adjacent to their low tide refuge. The results of three national tagging programs were analysed to determine the movement patterns of adolescent and adult fishes. The coast-wide ORI-WWF National Voluntary Tagging Program and two dedicated research programs in marine protected areas (MPAs) at De Hoop MPA and Tsitsikamma National Park (TNP) recorded few large-scale movements of tagged adult blacktail, zebra and juvenile musselcracker. High spatial-resolution data from the TNP suggested movements were usually on scales far smaller than one km. Together with long periods at liberty for many recaptured individuals, this suggests these fishes are longterm residents of small home range areas. However, tagged musselcracker over 600 mm forklength (adults) were observed to make large-scale movements, including some in excess of 800 km from Eastern Cape to KwaZulu-Natal waters. Predominantly eastward movements of adults recaptured during the spawning season indicate seasonal spawning migrations that occur in different regions of the coast. These enable the use of prevailing oceanographic currents to disperse eggs and larvae to suitable rocky nursery habitat. The third component of this study made use of high-resolution data on the temporal and spatial distribution of catches by scientific angling in the TNP to examine the daily activity patterns of the study species in relation to diel and tidal cycles, and habitat use. Blacktail capture probability was correlated with the diurnal light cycle, with peaks close to twilight suggesting elevated crepuscular foraging activity. Catches of blacktail, zebra and small musselcracker were correlated with the tidal cycle, foraging peaking over high tide periods. All three species used shallow inshore habitats extensively for foraging, blacktail showing a preference for sandy areas, while zebra and small musselcracker preferred shallow reef. Capture probability of larger musselcracker, however, was unrelated to habitat, possibly evidence of increasing area and habitat use with an ontogenetic change in diet. The lifetime movement patterns of these three species are discussed in relation to conservation measures and their management in South African fisheries. Restricted movement throughout post-settlement life for blacktail and zebra, and during the juvenile phase for musselcracker, makes local populations vulnerable to overexploitation. At present, MPAs probably play an important role in protecting local blacktail and zebra populations from overexploitation, and limited post-settlement movements mean the degree of larval dispersal between protected and adjacent areas will likely determine the effectiveness of MPAs in enhancing fisheries for these species. By contrast, MPAs likely provide recruits to fisheries for musselcracker during ontogenetic movements and dispersal from MPAs during spawning migrations. MPAs only offer partial protection to adult musselcracker populations in the spawning season, but this could nevertheless be significant under high levels of exploitation.
- Full Text:
- Date Issued: 2009
- Authors: Watt-Pringle, Peter Andrew
- Date: 2009
- Subjects: Sparidae -- South Africa , Diplodus , Sparodon Durbanensis , Fisheries -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5302 , http://hdl.handle.net/10962/d1005147 , Sparidae -- South Africa , Diplodus , Sparodon Durbanensis , Fisheries -- South Africa
- Description: This study investigated the movement behaviour of three inshore South African sparids – blacktail (Diplodus sargus capensis), zebra (Diplodus cervinus hottentotus) and white musselcracker (Sparodon durbanensis), popular inshore fishery species caught in appreciable numbers along much of the South African coast. The first study component examined movements of juveniles in a rocky intertidal nursery area at Schoenmakerskop near Port Elizabeth. Juveniles in a single gully were tagged with Visible Implant Elastomer (VIE) and resighted at the study site on snorkelling gear over a seven-month period. Tagged zebra and musselcracker displayed limited movement between potential low tide refuges, being observed repeatedly in the same gully over the full duration of the study. However, blacktail displayed greater movements and were seen infrequently in the later period of the study, probably having undergone an ontogenetic habitat shift to subtidal areas. There was evidence that blacktail maintain use of their intertidal nursery over high tide, during which the other two species moved into shallower areas adjacent to their low tide refuge. The results of three national tagging programs were analysed to determine the movement patterns of adolescent and adult fishes. The coast-wide ORI-WWF National Voluntary Tagging Program and two dedicated research programs in marine protected areas (MPAs) at De Hoop MPA and Tsitsikamma National Park (TNP) recorded few large-scale movements of tagged adult blacktail, zebra and juvenile musselcracker. High spatial-resolution data from the TNP suggested movements were usually on scales far smaller than one km. Together with long periods at liberty for many recaptured individuals, this suggests these fishes are longterm residents of small home range areas. However, tagged musselcracker over 600 mm forklength (adults) were observed to make large-scale movements, including some in excess of 800 km from Eastern Cape to KwaZulu-Natal waters. Predominantly eastward movements of adults recaptured during the spawning season indicate seasonal spawning migrations that occur in different regions of the coast. These enable the use of prevailing oceanographic currents to disperse eggs and larvae to suitable rocky nursery habitat. The third component of this study made use of high-resolution data on the temporal and spatial distribution of catches by scientific angling in the TNP to examine the daily activity patterns of the study species in relation to diel and tidal cycles, and habitat use. Blacktail capture probability was correlated with the diurnal light cycle, with peaks close to twilight suggesting elevated crepuscular foraging activity. Catches of blacktail, zebra and small musselcracker were correlated with the tidal cycle, foraging peaking over high tide periods. All three species used shallow inshore habitats extensively for foraging, blacktail showing a preference for sandy areas, while zebra and small musselcracker preferred shallow reef. Capture probability of larger musselcracker, however, was unrelated to habitat, possibly evidence of increasing area and habitat use with an ontogenetic change in diet. The lifetime movement patterns of these three species are discussed in relation to conservation measures and their management in South African fisheries. Restricted movement throughout post-settlement life for blacktail and zebra, and during the juvenile phase for musselcracker, makes local populations vulnerable to overexploitation. At present, MPAs probably play an important role in protecting local blacktail and zebra populations from overexploitation, and limited post-settlement movements mean the degree of larval dispersal between protected and adjacent areas will likely determine the effectiveness of MPAs in enhancing fisheries for these species. By contrast, MPAs likely provide recruits to fisheries for musselcracker during ontogenetic movements and dispersal from MPAs during spawning migrations. MPAs only offer partial protection to adult musselcracker populations in the spawning season, but this could nevertheless be significant under high levels of exploitation.
- Full Text:
- Date Issued: 2009
Myth, Music & Modernism: the Wagnerian dimension in Virginia Woolf's Mrs Dalloway and the waves and James Joyce’s Finnegans Wake
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
National identity and nation-building in post-apartheid South Africa
- Authors: Stinson, Andrew Todd
- Date: 2009
- Subjects: Post-apartheid era -- South Africa , South Africa -- Politics and government -- 1994- , Nationalism -- South Africa , Civil society -- South Africa , Democracy -- South Africa , South Africa -- Social policy , Ethnicity -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2832 , http://hdl.handle.net/10962/d1003042
- Description: Throughout South Africa’s post-Apartheid history, the ANC-led government has undertaken a distinct nation-building program in pursuit of “a truly united, democratic and prosperous South Africa” (ANC, 2007). This is reflected in a two-pronged approach, coupling political and socioeconomic transformation with the social-psychological aspect of forging a broad and inclusive national consciousness. The ANC’s “rainbow nation” approach embraces cultural diversity through what I shall call the practice of “interculturalism”. Interculturalism is a way of recognizing commonalities, reducing tensions and promoting the formation of social partnerships among different cultural groups. The ANC has also promoted a civic culture based on the principles of liberal democracy, non-racism, equality and the protection of individual rights. Interculturalism and civic nationalism are critically important factors to South African nation-building since together they foster a shared public culture and support meaningful participation in the creation of a truly just and democratic South Africa. Unfortunately, in many ways South African society remains deeply divided by race, ethnicity and economic inequality. This thesis analyses various theoretical approaches to national identity and nationbuilding with the aim of identifying several concepts which arguably throw light on the problems of South African nation-building and national identity formation. It is argued that interculturalism and civic nationalism are context appropriate approaches which have been adopted by the ANC to further an inclusive sense of shared public culture and promote participation in the creation of a shared public future. These approaches have led to the limited emergence of a broad South African national identity. However, South Africa’s commitment to socio-economic transformation has been less successful in generating widespread support for a broad national identity. While some of those previously disadvantaged under Apartheid have benefited from poverty alleviation schemes, service delivery initiatives and black economic empowerment programs, many continue to suffer from homelessness, unemployment and worsening economic conditions. Increasing economic marginalization has caused growing discontent among South Africa’s poor and constitutes the biggest threat to the formation of a cohesive national identity in South African society. Ultimately, it is argued that while interculturalism and civic nationalism have played an important role in fostering the growth of a broad national identity, true South African social cohesion will fail to emerge without a massive and sustained commitment to wide-ranging socio-economic transformation.
- Full Text:
- Date Issued: 2009
- Authors: Stinson, Andrew Todd
- Date: 2009
- Subjects: Post-apartheid era -- South Africa , South Africa -- Politics and government -- 1994- , Nationalism -- South Africa , Civil society -- South Africa , Democracy -- South Africa , South Africa -- Social policy , Ethnicity -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2832 , http://hdl.handle.net/10962/d1003042
- Description: Throughout South Africa’s post-Apartheid history, the ANC-led government has undertaken a distinct nation-building program in pursuit of “a truly united, democratic and prosperous South Africa” (ANC, 2007). This is reflected in a two-pronged approach, coupling political and socioeconomic transformation with the social-psychological aspect of forging a broad and inclusive national consciousness. The ANC’s “rainbow nation” approach embraces cultural diversity through what I shall call the practice of “interculturalism”. Interculturalism is a way of recognizing commonalities, reducing tensions and promoting the formation of social partnerships among different cultural groups. The ANC has also promoted a civic culture based on the principles of liberal democracy, non-racism, equality and the protection of individual rights. Interculturalism and civic nationalism are critically important factors to South African nation-building since together they foster a shared public culture and support meaningful participation in the creation of a truly just and democratic South Africa. Unfortunately, in many ways South African society remains deeply divided by race, ethnicity and economic inequality. This thesis analyses various theoretical approaches to national identity and nationbuilding with the aim of identifying several concepts which arguably throw light on the problems of South African nation-building and national identity formation. It is argued that interculturalism and civic nationalism are context appropriate approaches which have been adopted by the ANC to further an inclusive sense of shared public culture and promote participation in the creation of a shared public future. These approaches have led to the limited emergence of a broad South African national identity. However, South Africa’s commitment to socio-economic transformation has been less successful in generating widespread support for a broad national identity. While some of those previously disadvantaged under Apartheid have benefited from poverty alleviation schemes, service delivery initiatives and black economic empowerment programs, many continue to suffer from homelessness, unemployment and worsening economic conditions. Increasing economic marginalization has caused growing discontent among South Africa’s poor and constitutes the biggest threat to the formation of a cohesive national identity in South African society. Ultimately, it is argued that while interculturalism and civic nationalism have played an important role in fostering the growth of a broad national identity, true South African social cohesion will fail to emerge without a massive and sustained commitment to wide-ranging socio-economic transformation.
- Full Text:
- Date Issued: 2009
Normative indicators for a black, Xhosa speaking population without tertiary education on four tests used to access malingering
- Authors: Wong, Andrea Jane
- Date: 2009
- Subjects: Malingering Neuropsychological tests Language and languages -- Ability testing Educational tests and measurements Education evaluation Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3088 , http://hdl.handle.net/10962/d1002597
- Description: Malingering has become an increasing concern in neuropsychological assessment in recent years, and a wide range of tests have been designed and examined for the purpose of detecting malingering. Cut-off scores have been recommended for these tests in order to provide indications of malingering performances. However, the derived scores have been in respect of westernised populations of people with relatively high levels of education who speak English as their first language. Accordingly, the current study aimed to attain normative data and cut-off scores for four commonly employed neuropsychological tools, administered in English, on a population of black, South African, Xhosa-speaking people (N = 33), who attended a former DET-type school in the Eastern Cape, with a Grade 11-12 level of education, in the age range of 18 - 40 years. The targeted measures included the TOMM, the Rey-15 Item Memory Test, the Digit Span subtest of the WAIS-III, and the Trail Making Test. The obtained scores were poorer than the previously published cut-offs for at least one component of each of the tests investigated, except the TOMM. The fmdings of this study highlight the important role that the factors of culture, quality of education, and language play in neuropsychological test performance.
- Full Text:
- Date Issued: 2009
- Authors: Wong, Andrea Jane
- Date: 2009
- Subjects: Malingering Neuropsychological tests Language and languages -- Ability testing Educational tests and measurements Education evaluation Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3088 , http://hdl.handle.net/10962/d1002597
- Description: Malingering has become an increasing concern in neuropsychological assessment in recent years, and a wide range of tests have been designed and examined for the purpose of detecting malingering. Cut-off scores have been recommended for these tests in order to provide indications of malingering performances. However, the derived scores have been in respect of westernised populations of people with relatively high levels of education who speak English as their first language. Accordingly, the current study aimed to attain normative data and cut-off scores for four commonly employed neuropsychological tools, administered in English, on a population of black, South African, Xhosa-speaking people (N = 33), who attended a former DET-type school in the Eastern Cape, with a Grade 11-12 level of education, in the age range of 18 - 40 years. The targeted measures included the TOMM, the Rey-15 Item Memory Test, the Digit Span subtest of the WAIS-III, and the Trail Making Test. The obtained scores were poorer than the previously published cut-offs for at least one component of each of the tests investigated, except the TOMM. The fmdings of this study highlight the important role that the factors of culture, quality of education, and language play in neuropsychological test performance.
- Full Text:
- Date Issued: 2009
Organizational culture and innovation: the case of the Namibian National Institute for Educational Development
- Piepmeyer, Gernot Maximilian
- Authors: Piepmeyer, Gernot Maximilian
- Date: 2009
- Subjects: National Institute for Educational Development (Namibia) Corporate culture -- Namibia Organizational behavior -- Namibia Technological innovations -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1685 , http://hdl.handle.net/10962/d1003568
- Description: The purpose of my research is to diagnose the organizational culture of the National Institute for Educational Development [NIED] , in particular to determine whether it is conducive to innovation, as was envisaged at the time of its inception. The diagnosis of NIED's organizational culture was done by using a hybrid qualitative and quantitative case study. A questionnaire, the Cameron and Quinn's Organizational Culture Assessment Instrument [OCAI], was given to all professional members at NIED, while six members of the NIED organization were interviewed. It emerged from the data, first, that the characteristics of the dominant NIED culture, using Cameron and Quinn's six dimensions of culture that produced an "overall culture profile" of NIED, are not likely to enhance innovativeness. Nevertheless, there is a strong preference towards a culture type favourable to innovation. Second, there are cultural factors antithetical to an innovative organizational culture. These include poor information flow and a lack of communication, negligible crossfunction interaction and freedom, and constraining hierarchical and bureaucratic structures. Third, NIED has, in the form of a "green paper," a set of critical norms, values and assumptions that characterize the culture of innovative organizations. Finally, there is evidence of the presence of cultural characteristics conducive to an innovative organizational culture. These include: learning how to learn; being pro-active in initiating change and innovativeness; and sustaining momentum, consistency and perseverance. The discrepancy between the existing organizational culture and the preferred organizational culture revealed by the overall cultural profile can be explained by the fact that the norms, values and assumptions that characterize the culture of innovative organizations and the cultural characteristics conducive to an innovative organizational culture are not fully infused into the whole organization. There is a tension between NIED's bureaucratic nature and its innovative mission. Organizational culture change, where NIED's structures and processes are aligned with its espoused vision and mission, is needed in order for it to be better placed to achieve its original pioneering mandate.
- Full Text:
- Date Issued: 2009
- Authors: Piepmeyer, Gernot Maximilian
- Date: 2009
- Subjects: National Institute for Educational Development (Namibia) Corporate culture -- Namibia Organizational behavior -- Namibia Technological innovations -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1685 , http://hdl.handle.net/10962/d1003568
- Description: The purpose of my research is to diagnose the organizational culture of the National Institute for Educational Development [NIED] , in particular to determine whether it is conducive to innovation, as was envisaged at the time of its inception. The diagnosis of NIED's organizational culture was done by using a hybrid qualitative and quantitative case study. A questionnaire, the Cameron and Quinn's Organizational Culture Assessment Instrument [OCAI], was given to all professional members at NIED, while six members of the NIED organization were interviewed. It emerged from the data, first, that the characteristics of the dominant NIED culture, using Cameron and Quinn's six dimensions of culture that produced an "overall culture profile" of NIED, are not likely to enhance innovativeness. Nevertheless, there is a strong preference towards a culture type favourable to innovation. Second, there are cultural factors antithetical to an innovative organizational culture. These include poor information flow and a lack of communication, negligible crossfunction interaction and freedom, and constraining hierarchical and bureaucratic structures. Third, NIED has, in the form of a "green paper," a set of critical norms, values and assumptions that characterize the culture of innovative organizations. Finally, there is evidence of the presence of cultural characteristics conducive to an innovative organizational culture. These include: learning how to learn; being pro-active in initiating change and innovativeness; and sustaining momentum, consistency and perseverance. The discrepancy between the existing organizational culture and the preferred organizational culture revealed by the overall cultural profile can be explained by the fact that the norms, values and assumptions that characterize the culture of innovative organizations and the cultural characteristics conducive to an innovative organizational culture are not fully infused into the whole organization. There is a tension between NIED's bureaucratic nature and its innovative mission. Organizational culture change, where NIED's structures and processes are aligned with its espoused vision and mission, is needed in order for it to be better placed to achieve its original pioneering mandate.
- Full Text:
- Date Issued: 2009
Phenolic compounds in water and the implications for rapid detection of indicator micro-organisms using ß-D-Galactosidase and ß-D-Glucuronidase
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
Photophysical and photochemical behaviour of metallophthalocyanines effect of nanoparticles and molecules of biological importance
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
- Full Text:
- Date Issued: 2009
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
- Full Text:
- Date Issued: 2009
Photosynthetic and evolutionary determinants of the response of selected C3 and C4 (NADP-ME) grasses to fire
- Authors: Martin, Tarryn
- Date: 2009
- Subjects: Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4211 , http://hdl.handle.net/10962/d1003780 , Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Description: Species possess characteristics that are considered adapted to burning and these allow them to outcompete species and dominate in fire prone environments. It has therefore been proposed that fire might have played a critical role in the observed expansion of the grasslands, during the late Miocene. The aim of this study was (i) to investigate whether plant response to fire was a result of physiology or (ii) whether it was due to phylogenetic history. This was achieved by doing a pair-wise comparison between Panicoideae (and Panicoideae) and non-Panicoideae (Danthonioideae and Aristidoideae) species. Pre-fire characteristics, that would enhance fire frequency and assist with plant recovery after burning, were compared across phylogenies and photosynthetic type. Post fire plant recovery was then followed in a field and pot comparison which examined the re-growth of the leaf canopy area, leaf mass, above-ground biomass and the cost of this to the below-ground biomass. The pre-fire characteristics showed both a photosynthetic and phylogenetic response. It was found that the species showed a greater canopy death during winter and had a lower moisture content than the species. These characteristics would potentially contribute towards a larger fuel load in the species. However, the comparison of the dead standing biomass at the end of winter and the below-ground biomass, showed a phylogenetic response with the Panicoideae having a proportionally larger dead standing biomass and below-ground biomass than the non-Panicoideae. These results suggest that not only did the Panicoideae have a larger potential fuel load but that they also shunted carbon below-ground, enabling a fast recovery after being burned. The post-fire results were more strongly determined by phylogeny than by photosynthetic type. The Panicoideae recovered faster and more completely than the non-Panicoideae grasses, possibly contributing to their success and expansion under conditions of increased fire frequency. Although recovery of the and Panicoideae were similar, frequently burnt grasslands are dominated by the Panicoideae. Hence, this dominance cannot be explained by differences in their fire responses and may be determined by the post-fire environmental conditions that potentially advantage species possessing the photosynthetic pathway. Panicoideae dominance is limited to mesic environments where fire is the likely driver of grassland expansion while more arid environments are dominated by non-Panicoideae species. Representative species from these non-Panicoid subfamilies showed poor recovery after fire. This suggests that factors other than fire were the likely drivers of these xeric grassland expansions. The ability of these subfamilies, and particularly the species, to cope with drought remains a likely selective mechanism that requires further research.
- Full Text:
- Date Issued: 2009
- Authors: Martin, Tarryn
- Date: 2009
- Subjects: Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4211 , http://hdl.handle.net/10962/d1003780 , Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Description: Species possess characteristics that are considered adapted to burning and these allow them to outcompete species and dominate in fire prone environments. It has therefore been proposed that fire might have played a critical role in the observed expansion of the grasslands, during the late Miocene. The aim of this study was (i) to investigate whether plant response to fire was a result of physiology or (ii) whether it was due to phylogenetic history. This was achieved by doing a pair-wise comparison between Panicoideae (and Panicoideae) and non-Panicoideae (Danthonioideae and Aristidoideae) species. Pre-fire characteristics, that would enhance fire frequency and assist with plant recovery after burning, were compared across phylogenies and photosynthetic type. Post fire plant recovery was then followed in a field and pot comparison which examined the re-growth of the leaf canopy area, leaf mass, above-ground biomass and the cost of this to the below-ground biomass. The pre-fire characteristics showed both a photosynthetic and phylogenetic response. It was found that the species showed a greater canopy death during winter and had a lower moisture content than the species. These characteristics would potentially contribute towards a larger fuel load in the species. However, the comparison of the dead standing biomass at the end of winter and the below-ground biomass, showed a phylogenetic response with the Panicoideae having a proportionally larger dead standing biomass and below-ground biomass than the non-Panicoideae. These results suggest that not only did the Panicoideae have a larger potential fuel load but that they also shunted carbon below-ground, enabling a fast recovery after being burned. The post-fire results were more strongly determined by phylogeny than by photosynthetic type. The Panicoideae recovered faster and more completely than the non-Panicoideae grasses, possibly contributing to their success and expansion under conditions of increased fire frequency. Although recovery of the and Panicoideae were similar, frequently burnt grasslands are dominated by the Panicoideae. Hence, this dominance cannot be explained by differences in their fire responses and may be determined by the post-fire environmental conditions that potentially advantage species possessing the photosynthetic pathway. Panicoideae dominance is limited to mesic environments where fire is the likely driver of grassland expansion while more arid environments are dominated by non-Panicoideae species. Representative species from these non-Panicoid subfamilies showed poor recovery after fire. This suggests that factors other than fire were the likely drivers of these xeric grassland expansions. The ability of these subfamilies, and particularly the species, to cope with drought remains a likely selective mechanism that requires further research.
- Full Text:
- Date Issued: 2009
Phylogeography and epifauna of two intertidal seaweeds on the coast of South Africa
- Authors: Mmonwa, Lucas Kolobe
- Date: 2009
- Subjects: Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5738 , http://hdl.handle.net/10962/d1005424 , Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Description: Southern African biogeographic boundaries delimit the phylogeographic distribution of some coastal and estuarine invertebrates. This study investigated the impact of these boundaries on the phylogeographic distribution of two intertidal red seaweeds, Gelidium pristoides and Hypnea spicifera using the mitochondrial Cox2-3 spacer and the nuclear ITS1 regions. G. pristoides spores have short distance-dispersal, while long distance-dispersal is more likely in H. spicifera via spores and drifting fertile thallus fragments. Both markers revealed a south-western and south-eastern lineage within G. pristoides but the breaks between lineages do not coincide with any recognised biogeographic limits. The Cox2-3 spacer revealed a boundary between the two lineages at the Alexandria Coastal Dunefield (ACD) and ITS1 at the Gamtoos-Van Stadens Dunefields (GVD) which is approximately 80km west of the ACD. The minor difference between the two markers regarding location of the phylogeographic boundary is probably due to the dating differences between the two dunefields. The ACD as developed currently is superimposed on the ancient dunefields which formed during the Pleistocene, coinciding with the Cox2-3 spacer sequences divergence which dates back 500,000 - 580,000 years. The GVD formed during the Holocene (6,500 - 4,000 years ago), coinciding with the ITS1 sequences divergence which dates 4,224 - 4,928 years ago. Thus, these phylogeographic boundaries probably appeared without the influence of biogeographic boundaries, but rather due to the lack of suitable habitat in the dunefields, coupled with short dispersal-distances of the spores. Analysis of the ITS1 and Cox2-3 spacer regions in H. spicifera revealed that the species is characterized by uniform genetic structure along the coastline. This reflects the species`s potential for long range expansion as it inhabits both the intertidal and subtidal zones; and this presumably leads to high gene flow among populations. The ITS1 sequences showed minimal genetic variation of one substitution between the gametophyte and tetrasporophyte generations within H. spicifera. This suggests the predominance of asexual reproduction, which reduces gene flow and fixes alleles between generations. ANOSIM and Bray-Curtis cluster analyses showed scale-dependant variation in the abundances of epifauna (mainly amphipod, isopod, mollusc and polychaete species) on G. pristoides. At small local (within site) and large (among sites) scales, there were weak and no structure in epifaunal abundances respectively. However, at larger, biogeographic scales, samples from the same biogeographic region tended to be clustered together. Thus, there was a group containing predominantly south coast samples and a group containing east coast samples mixed with the remaining south coast samples. Such scale-dependant variation in epifaunal abundances is probably due to the effects of factors driving species richness at small local (within site) scales (e.g. wave exposure, seaweed biomass) and at larger, biogeographic scales (e.g. surface sea temperature). Moreover, at very small (individual samples) scales; there was no correlation between epifauna composition and genotype of the seaweed. Seaweed samples characterized by distinct ITS1 or Cox2-3 spacer sequences did not show any significant differences in epifaunal composition. Although the distributional pattern of the epifaunal community observed at large biogeographic scale is not clear, it seems to be associated with the biogeographic regions. However, phylogeographic distribution of Gelidium pristoides is not connected to biogeographic regions. Thus, at larger, biogeographic scales, there is no correlation between phylogeographic distribution of G. pristoides and distribution of the associated fauna
- Full Text:
- Date Issued: 2009
- Authors: Mmonwa, Lucas Kolobe
- Date: 2009
- Subjects: Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5738 , http://hdl.handle.net/10962/d1005424 , Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Description: Southern African biogeographic boundaries delimit the phylogeographic distribution of some coastal and estuarine invertebrates. This study investigated the impact of these boundaries on the phylogeographic distribution of two intertidal red seaweeds, Gelidium pristoides and Hypnea spicifera using the mitochondrial Cox2-3 spacer and the nuclear ITS1 regions. G. pristoides spores have short distance-dispersal, while long distance-dispersal is more likely in H. spicifera via spores and drifting fertile thallus fragments. Both markers revealed a south-western and south-eastern lineage within G. pristoides but the breaks between lineages do not coincide with any recognised biogeographic limits. The Cox2-3 spacer revealed a boundary between the two lineages at the Alexandria Coastal Dunefield (ACD) and ITS1 at the Gamtoos-Van Stadens Dunefields (GVD) which is approximately 80km west of the ACD. The minor difference between the two markers regarding location of the phylogeographic boundary is probably due to the dating differences between the two dunefields. The ACD as developed currently is superimposed on the ancient dunefields which formed during the Pleistocene, coinciding with the Cox2-3 spacer sequences divergence which dates back 500,000 - 580,000 years. The GVD formed during the Holocene (6,500 - 4,000 years ago), coinciding with the ITS1 sequences divergence which dates 4,224 - 4,928 years ago. Thus, these phylogeographic boundaries probably appeared without the influence of biogeographic boundaries, but rather due to the lack of suitable habitat in the dunefields, coupled with short dispersal-distances of the spores. Analysis of the ITS1 and Cox2-3 spacer regions in H. spicifera revealed that the species is characterized by uniform genetic structure along the coastline. This reflects the species`s potential for long range expansion as it inhabits both the intertidal and subtidal zones; and this presumably leads to high gene flow among populations. The ITS1 sequences showed minimal genetic variation of one substitution between the gametophyte and tetrasporophyte generations within H. spicifera. This suggests the predominance of asexual reproduction, which reduces gene flow and fixes alleles between generations. ANOSIM and Bray-Curtis cluster analyses showed scale-dependant variation in the abundances of epifauna (mainly amphipod, isopod, mollusc and polychaete species) on G. pristoides. At small local (within site) and large (among sites) scales, there were weak and no structure in epifaunal abundances respectively. However, at larger, biogeographic scales, samples from the same biogeographic region tended to be clustered together. Thus, there was a group containing predominantly south coast samples and a group containing east coast samples mixed with the remaining south coast samples. Such scale-dependant variation in epifaunal abundances is probably due to the effects of factors driving species richness at small local (within site) scales (e.g. wave exposure, seaweed biomass) and at larger, biogeographic scales (e.g. surface sea temperature). Moreover, at very small (individual samples) scales; there was no correlation between epifauna composition and genotype of the seaweed. Seaweed samples characterized by distinct ITS1 or Cox2-3 spacer sequences did not show any significant differences in epifaunal composition. Although the distributional pattern of the epifaunal community observed at large biogeographic scale is not clear, it seems to be associated with the biogeographic regions. However, phylogeographic distribution of Gelidium pristoides is not connected to biogeographic regions. Thus, at larger, biogeographic scales, there is no correlation between phylogeographic distribution of G. pristoides and distribution of the associated fauna
- Full Text:
- Date Issued: 2009
Plants for health, life and spirit in Africa : implications for biodiversity and cultural diversity conservation
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6617 , http://hdl.handle.net/10962/d1016225
- Description: [From Introduction] Natural resources are often only perceived as contributing to rural livelihoods through food production and household welfare. There is a growing wealth of information capturing the direct-use values of the environment and consequent recognition of natural resources as being “the poor man's overcoat”. These approaches, however, have failed to fully account for the various ways in which different groups of people make use of, and find value in biodiversity. New developments within the field of anthropology have begun to explore the relationship between biodiversity and human diversity. This view has largely come about because many of the areas of highest biological diversity are inhabited by indigenous and traditional people, providing what the Declaration of Belem (1988) calls an 'inextricable link' between biological and cultural diversity (Posey 1999). The term bio-cultural diversity was introduced by Posey in 1999 to describe the concept denoting this link. , Funding was received from the South Africa-Netherlands Programme on Alternatives in Development (SANPAD) and the International Foundation of Science (IFS)
- Full Text:
- Date Issued: 2009
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6617 , http://hdl.handle.net/10962/d1016225
- Description: [From Introduction] Natural resources are often only perceived as contributing to rural livelihoods through food production and household welfare. There is a growing wealth of information capturing the direct-use values of the environment and consequent recognition of natural resources as being “the poor man's overcoat”. These approaches, however, have failed to fully account for the various ways in which different groups of people make use of, and find value in biodiversity. New developments within the field of anthropology have begun to explore the relationship between biodiversity and human diversity. This view has largely come about because many of the areas of highest biological diversity are inhabited by indigenous and traditional people, providing what the Declaration of Belem (1988) calls an 'inextricable link' between biological and cultural diversity (Posey 1999). The term bio-cultural diversity was introduced by Posey in 1999 to describe the concept denoting this link. , Funding was received from the South Africa-Netherlands Programme on Alternatives in Development (SANPAD) and the International Foundation of Science (IFS)
- Full Text:
- Date Issued: 2009
Polymers, catalysts and nanostructures a hybrid approach to biomolecule detection
- Authors: Frith, Kelly-Anne
- Date: 2009
- Subjects: Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3980 , http://hdl.handle.net/10962/d1004039 , Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Description: The main goals in electroanalytical sensing are towards improved sensitivity and selectivity, or specificity, of an analyte. There are several approaches to achieving these goals with the main approach being modification of an electrode surface with synthetic or natural catalysts (enzymes), polymers and also utilisation of nanostructured materials. At present, there is a strong movement towards hybrid sensing which couple different properties of two or more surface modification approaches. In this thesis, a range of these surface modifications were explored for analysis and detection of two main analytes: the amino acid, tryptophan (Trp); and, the neurotransmitter, dopamine (DA). Specifically, this thesis aimed to utilise these methods to enhance the sensitivity and selectivity for Trp over an interferent, the indoleamine, melatonin (Mel); and, DA over the vitamin, ascorbic acid (AA). For Trp detection, immobilisation of an enzyme, Tryptophanase (Trpase) resulted in poor selectivity for the analyte. However, enhanced sensitivity and selectivity was achieved through pH manipulation of the electrolyte medium at a Nafion®-modified electrode surface for both Trp and Mel. At pH 3.0, the Mel and Trp anodic peak potentials were sufficiently resolved allowing for an LOD of 1.60 and 1.62 nM,respectively, and permitting the accurate analysis of Trp in a dietary supplement containing Mel. Multi-walled carbon nanotubes (MWCNTs) suspended in Nafion® exhibited further increases in the signal responses of these analytes at pH 3.0 and 7.4 with minimal change in the resolution of the anodic peaks. A lower sensitivity was, therefore, observed at the Nafion® and MWCNT modified electrode compared to the Nafion®-modified electrode at pH 3.0 with LODs of 0.59 and 0.80 nM exhibited for Trp and Mel, respectively. Enhanced selectivity for Trp in the presence of Mel can be achieved with MWCNTs in the presence of metallotetrasulphonated phthalocyanines (MTSPcs) particularly at pH 3.0, owing to cation exchange effects. However, the lack of sensitivity towards Trp, and even Mel, at this CoTSPc and MWCNT modified electrode remains a drawback. For DA, detection at the MWCNT and Nafion® surface resulted in improved sensitivity over that of both the bare electrode (613.0 nM) and the Nafion® modified electrode (1045.1 nM) with a calculated LOD of 133.9 nM at this layer. Furthermore, improvements in the selectivity of DA were achieved at the Nafion® and MWCNT modified electrode as exclusion of AA (150 μM) was achieved. At the MWCNT and CoTSPc surface, AA was excluded up to 130 μM with sensitivity for DA extending as low as 14.3 nM, far greater than observed for Trp and Mel. These concentrations are well within physiological concentration ranges and represent the most significant solution yet in terms of AA exclusion and enhanced sensitivity for DA. An examination of the surface layering by impedance spectroscopy and atomic force microscopy indicates that the success of the hybrid sensor utilising CoTSPc and MWCNTs lay in improved dispersion of MWCNTs and improved electron transfer kinetics, facilitated by the net charge of the materials present. This thesis, thus, showed the utility of a judicious selection of synthetic and biological catalysts, polymers and carbon nanomaterials towards a hybrid approach to the electrochemical sensing of Trp, Mel, DA and AA with focus on sensitivity and selectivity of these analytes.
- Full Text:
- Date Issued: 2009
- Authors: Frith, Kelly-Anne
- Date: 2009
- Subjects: Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3980 , http://hdl.handle.net/10962/d1004039 , Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Description: The main goals in electroanalytical sensing are towards improved sensitivity and selectivity, or specificity, of an analyte. There are several approaches to achieving these goals with the main approach being modification of an electrode surface with synthetic or natural catalysts (enzymes), polymers and also utilisation of nanostructured materials. At present, there is a strong movement towards hybrid sensing which couple different properties of two or more surface modification approaches. In this thesis, a range of these surface modifications were explored for analysis and detection of two main analytes: the amino acid, tryptophan (Trp); and, the neurotransmitter, dopamine (DA). Specifically, this thesis aimed to utilise these methods to enhance the sensitivity and selectivity for Trp over an interferent, the indoleamine, melatonin (Mel); and, DA over the vitamin, ascorbic acid (AA). For Trp detection, immobilisation of an enzyme, Tryptophanase (Trpase) resulted in poor selectivity for the analyte. However, enhanced sensitivity and selectivity was achieved through pH manipulation of the electrolyte medium at a Nafion®-modified electrode surface for both Trp and Mel. At pH 3.0, the Mel and Trp anodic peak potentials were sufficiently resolved allowing for an LOD of 1.60 and 1.62 nM,respectively, and permitting the accurate analysis of Trp in a dietary supplement containing Mel. Multi-walled carbon nanotubes (MWCNTs) suspended in Nafion® exhibited further increases in the signal responses of these analytes at pH 3.0 and 7.4 with minimal change in the resolution of the anodic peaks. A lower sensitivity was, therefore, observed at the Nafion® and MWCNT modified electrode compared to the Nafion®-modified electrode at pH 3.0 with LODs of 0.59 and 0.80 nM exhibited for Trp and Mel, respectively. Enhanced selectivity for Trp in the presence of Mel can be achieved with MWCNTs in the presence of metallotetrasulphonated phthalocyanines (MTSPcs) particularly at pH 3.0, owing to cation exchange effects. However, the lack of sensitivity towards Trp, and even Mel, at this CoTSPc and MWCNT modified electrode remains a drawback. For DA, detection at the MWCNT and Nafion® surface resulted in improved sensitivity over that of both the bare electrode (613.0 nM) and the Nafion® modified electrode (1045.1 nM) with a calculated LOD of 133.9 nM at this layer. Furthermore, improvements in the selectivity of DA were achieved at the Nafion® and MWCNT modified electrode as exclusion of AA (150 μM) was achieved. At the MWCNT and CoTSPc surface, AA was excluded up to 130 μM with sensitivity for DA extending as low as 14.3 nM, far greater than observed for Trp and Mel. These concentrations are well within physiological concentration ranges and represent the most significant solution yet in terms of AA exclusion and enhanced sensitivity for DA. An examination of the surface layering by impedance spectroscopy and atomic force microscopy indicates that the success of the hybrid sensor utilising CoTSPc and MWCNTs lay in improved dispersion of MWCNTs and improved electron transfer kinetics, facilitated by the net charge of the materials present. This thesis, thus, showed the utility of a judicious selection of synthetic and biological catalysts, polymers and carbon nanomaterials towards a hybrid approach to the electrochemical sensing of Trp, Mel, DA and AA with focus on sensitivity and selectivity of these analytes.
- Full Text:
- Date Issued: 2009
Predictability of Geomagnetically Induced Currents using neural networks
- Authors: Lotz, Stefan
- Date: 2009
- Subjects: Advanced Composition Explorer (Artificial satellite) , Geomagnetism , Electromagnetic induction , Neural networks (Computer science) , Artificial intelligence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5483 , http://hdl.handle.net/10962/d1005269 , Advanced Composition Explorer (Artificial satellite) , Geomagnetism , Electromagnetic induction , Neural networks (Computer science) , Artificial intelligence
- Description: It is a well documented fact that Geomagnetically Induced Currents (GIC’s) poses a significant threat to ground-based electric conductor networks like oil pipelines, railways and powerline networks. A study is undertaken to determine the feasibility of using artificial neural network models to predict GIC occurrence in the Southern African power grid. The magnitude of an induced current at a specific location on the Earth’s surface is directly related to the temporal derivative of the geomagnetic field (specifically its horizontal components) at that point. Hence, the focus of the problem is on the prediction of the temporal variations in the horizontal geomagnetic field (@Bx/@t and @By/@t). Artificial neural networks are used to predict @Bx/@t and @By/@t measured at Hermanus, South Africa (34.27◦ S, 19.12◦ E) with a 30 minute prediction lead time. As input parameters to the neural networks, insitu solar wind measurements made by the Advanced Composition Explorer (ACE) satellite are used. The results presented here compare well with similar models developed at high-latitude locations (e.g. Sweden, Finland, Canada) where extensive GIC research has been undertaken. It is concluded that it would indeed be feasible to use a neural network model to predict GIC occurrence in the Southern African power grid, provided that GIC measurements, powerline configuration and network parameters are made available.
- Full Text:
- Date Issued: 2009
- Authors: Lotz, Stefan
- Date: 2009
- Subjects: Advanced Composition Explorer (Artificial satellite) , Geomagnetism , Electromagnetic induction , Neural networks (Computer science) , Artificial intelligence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5483 , http://hdl.handle.net/10962/d1005269 , Advanced Composition Explorer (Artificial satellite) , Geomagnetism , Electromagnetic induction , Neural networks (Computer science) , Artificial intelligence
- Description: It is a well documented fact that Geomagnetically Induced Currents (GIC’s) poses a significant threat to ground-based electric conductor networks like oil pipelines, railways and powerline networks. A study is undertaken to determine the feasibility of using artificial neural network models to predict GIC occurrence in the Southern African power grid. The magnitude of an induced current at a specific location on the Earth’s surface is directly related to the temporal derivative of the geomagnetic field (specifically its horizontal components) at that point. Hence, the focus of the problem is on the prediction of the temporal variations in the horizontal geomagnetic field (@Bx/@t and @By/@t). Artificial neural networks are used to predict @Bx/@t and @By/@t measured at Hermanus, South Africa (34.27◦ S, 19.12◦ E) with a 30 minute prediction lead time. As input parameters to the neural networks, insitu solar wind measurements made by the Advanced Composition Explorer (ACE) satellite are used. The results presented here compare well with similar models developed at high-latitude locations (e.g. Sweden, Finland, Canada) where extensive GIC research has been undertaken. It is concluded that it would indeed be feasible to use a neural network model to predict GIC occurrence in the Southern African power grid, provided that GIC measurements, powerline configuration and network parameters are made available.
- Full Text:
- Date Issued: 2009
Preservation or exploitation? : a study of the development of the mining rights legislation on the Witwatersrand goldfields from 1886 to 2008
- Authors: Stott, Joan
- Date: 2009
- Subjects: Ostrom, Elinor Chamber of Mines of South Africa Gold mines and mining -- South Africa -- Witwatersrand -- History Mineral industries -- Finance -- South Africa Mining law -- South Africa
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:988 , http://hdl.handle.net/10962/d1002723
- Description: Elinor Ostrom (2005: 238) assumes that in understanding the make up and behaviour of institutional systems governing natural resources: “Resource users are explicitly thought of as rational egoists who plunder local resources so as to maximise their own short-term benefits. Government officials are implicitly depicted, on the other hand, as seeking, the more general public interest, having the relevant information at hand and the capability of designing optimal policies.” This thesis examines the validity of this assumption through an historical analysis of the deep-level gold mining industry of the Witwatersrand, South Africa. The main focus of the assessment is on the institutions of ownership – that is, the development of mining rights and title legislation between 1886 and 2008. The study looks at the legislations’ transformation and implementation from the perspective of the gold mining industry – made up of the mining finance houses and the Chamber of Mines of South Africa – and that of the state. The transformation of the mining industry’s institutional framework was both a choice by government as well as that of the firms in the mining industry. The theoretical framework is constructed from four areas of economic thought. These include: the neoclassical and Keynesian schools of macroeconomic thought; industrial organisation and its relevance to the relationship between firms and the market; institutional and new institutional economics; and finally property rights. The determinants of policy design and the impact of such design on firms and industry is examined. The development, implementation and use of the aforementioned legislation is examined from two perspectives, namely, that of preserver or exploiter. Throughout the history of this prominent South African industry, the motivation for action from the industry or government has oscillated between the two extremes of preserver or exploiter over the time period examined. The conclusion is drawn on an overall and broad focus of actions – with a strong focus on the most recent developments in mining legislation – post-1992.
- Full Text:
- Date Issued: 2009
- Authors: Stott, Joan
- Date: 2009
- Subjects: Ostrom, Elinor Chamber of Mines of South Africa Gold mines and mining -- South Africa -- Witwatersrand -- History Mineral industries -- Finance -- South Africa Mining law -- South Africa
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:988 , http://hdl.handle.net/10962/d1002723
- Description: Elinor Ostrom (2005: 238) assumes that in understanding the make up and behaviour of institutional systems governing natural resources: “Resource users are explicitly thought of as rational egoists who plunder local resources so as to maximise their own short-term benefits. Government officials are implicitly depicted, on the other hand, as seeking, the more general public interest, having the relevant information at hand and the capability of designing optimal policies.” This thesis examines the validity of this assumption through an historical analysis of the deep-level gold mining industry of the Witwatersrand, South Africa. The main focus of the assessment is on the institutions of ownership – that is, the development of mining rights and title legislation between 1886 and 2008. The study looks at the legislations’ transformation and implementation from the perspective of the gold mining industry – made up of the mining finance houses and the Chamber of Mines of South Africa – and that of the state. The transformation of the mining industry’s institutional framework was both a choice by government as well as that of the firms in the mining industry. The theoretical framework is constructed from four areas of economic thought. These include: the neoclassical and Keynesian schools of macroeconomic thought; industrial organisation and its relevance to the relationship between firms and the market; institutional and new institutional economics; and finally property rights. The determinants of policy design and the impact of such design on firms and industry is examined. The development, implementation and use of the aforementioned legislation is examined from two perspectives, namely, that of preserver or exploiter. Throughout the history of this prominent South African industry, the motivation for action from the industry or government has oscillated between the two extremes of preserver or exploiter over the time period examined. The conclusion is drawn on an overall and broad focus of actions – with a strong focus on the most recent developments in mining legislation – post-1992.
- Full Text:
- Date Issued: 2009
Promoting indigenous vegetables in urban agriculture & livelihoods : policy lessons from Sub-Saharan Africa
- Shackleton, Charlie M, Pasquini, Margaret W, Ambrose-Oji, Bianca, Drescher, Axel W
- Authors: Shackleton, Charlie M , Pasquini, Margaret W , Ambrose-Oji, Bianca , Drescher, Axel W
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6619 , http://hdl.handle.net/10962/d1016227
- Description: [From Introduction] Globally, the growth of urbanised areas continues at an exponential rate, and most spectacularly in the developing world. The global urban population will increase from 2.9 billion in 2000 to 5.0 billion by 2030. The mean rate of urban growth in non-OECD countries between 2000 and 2005 was just under 3% per annum, compared to 0.5 % for rural regions of the same countries (UN-Habitat 2006). Although the proportion of Africans currently living in urban areas is the lowest in the world (+ 40%), because of this low base it is not unsurprising that the rates of urbanisation are among the highest at approximately 4.3% per annum. Projections vary, but sometime in the mid- 2020s over 50% of Africa's population will be living in urban areas, as compared to just 15% in 1950 and 34% in 1994. As urbanisation takes place another important trend is revealed, namely the locus of poverty in Africa is slowly shifting from rural to urban areas. For example, it is estimated that more than 56% of the world's absolute or chronic poor will be concentrated in urban areas (WRI 1996). Since as much as 60-80% of the income of the urban poor is spent on the purchase of food (Maxwell et al. 2000), the issue of food supply, both its quantity and quality, is increasingly a central issue in poverty reduction debates and strategies. In rural areas, a common strategy to alleviate poverty is to call for measures to boost small-holder food production. Surprisingly, this is less common in urban poverty alleviation programmes, despite the widespread promise of urban and household agriculture in contributing to improved food security.
- Full Text:
- Date Issued: 2009
- Authors: Shackleton, Charlie M , Pasquini, Margaret W , Ambrose-Oji, Bianca , Drescher, Axel W
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6619 , http://hdl.handle.net/10962/d1016227
- Description: [From Introduction] Globally, the growth of urbanised areas continues at an exponential rate, and most spectacularly in the developing world. The global urban population will increase from 2.9 billion in 2000 to 5.0 billion by 2030. The mean rate of urban growth in non-OECD countries between 2000 and 2005 was just under 3% per annum, compared to 0.5 % for rural regions of the same countries (UN-Habitat 2006). Although the proportion of Africans currently living in urban areas is the lowest in the world (+ 40%), because of this low base it is not unsurprising that the rates of urbanisation are among the highest at approximately 4.3% per annum. Projections vary, but sometime in the mid- 2020s over 50% of Africa's population will be living in urban areas, as compared to just 15% in 1950 and 34% in 1994. As urbanisation takes place another important trend is revealed, namely the locus of poverty in Africa is slowly shifting from rural to urban areas. For example, it is estimated that more than 56% of the world's absolute or chronic poor will be concentrated in urban areas (WRI 1996). Since as much as 60-80% of the income of the urban poor is spent on the purchase of food (Maxwell et al. 2000), the issue of food supply, both its quantity and quality, is increasingly a central issue in poverty reduction debates and strategies. In rural areas, a common strategy to alleviate poverty is to call for measures to boost small-holder food production. Surprisingly, this is less common in urban poverty alleviation programmes, despite the widespread promise of urban and household agriculture in contributing to improved food security.
- Full Text:
- Date Issued: 2009
Protein secondary structure prediction using neural networks and support vector machines
- Authors: Tsilo, Lipontseng Cecilia
- Date: 2009
- Subjects: Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5569 , http://hdl.handle.net/10962/d1002809 , Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Description: Predicting the secondary structure of proteins is important in biochemistry because the 3D structure can be determined from the local folds that are found in secondary structures. Moreover, knowing the tertiary structure of proteins can assist in determining their functions. The objective of this thesis is to compare the performance of Neural Networks (NN) and Support Vector Machines (SVM) in predicting the secondary structure of 62 globular proteins from their primary sequence. For each NN and SVM, we created six binary classifiers to distinguish between the classes’ helices (H) strand (E), and coil (C). For NN we use Resilient Backpropagation training with and without early stopping. We use NN with either no hidden layer or with one hidden layer with 1,2,...,40 hidden neurons. For SVM we use a Gaussian kernel with parameter fixed at = 0.1 and varying cost parameters C in the range [0.1,5]. 10- fold cross-validation is used to obtain overall estimates for the probability of making a correct prediction. Our experiments indicate for NN and SVM that the different binary classifiers have varying accuracies: from 69% correct predictions for coils vs. non-coil up to 80% correct predictions for stand vs. non-strand. It is further demonstrated that NN with no hidden layer or not more than 2 hidden neurons in the hidden layer are sufficient for better predictions. For SVM we show that the estimated accuracies do not depend on the value of the cost parameter. As a major result, we will demonstrate that the accuracy estimates of NN and SVM binary classifiers cannot distinguish. This contradicts a modern belief in bioinformatics that SVM outperforms other predictors.
- Full Text:
- Date Issued: 2009
- Authors: Tsilo, Lipontseng Cecilia
- Date: 2009
- Subjects: Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5569 , http://hdl.handle.net/10962/d1002809 , Neural networks (Computer science) , Support vector machines , Proteins -- Structure -- Mathematical models
- Description: Predicting the secondary structure of proteins is important in biochemistry because the 3D structure can be determined from the local folds that are found in secondary structures. Moreover, knowing the tertiary structure of proteins can assist in determining their functions. The objective of this thesis is to compare the performance of Neural Networks (NN) and Support Vector Machines (SVM) in predicting the secondary structure of 62 globular proteins from their primary sequence. For each NN and SVM, we created six binary classifiers to distinguish between the classes’ helices (H) strand (E), and coil (C). For NN we use Resilient Backpropagation training with and without early stopping. We use NN with either no hidden layer or with one hidden layer with 1,2,...,40 hidden neurons. For SVM we use a Gaussian kernel with parameter fixed at = 0.1 and varying cost parameters C in the range [0.1,5]. 10- fold cross-validation is used to obtain overall estimates for the probability of making a correct prediction. Our experiments indicate for NN and SVM that the different binary classifiers have varying accuracies: from 69% correct predictions for coils vs. non-coil up to 80% correct predictions for stand vs. non-strand. It is further demonstrated that NN with no hidden layer or not more than 2 hidden neurons in the hidden layer are sufficient for better predictions. For SVM we show that the estimated accuracies do not depend on the value of the cost parameter. As a major result, we will demonstrate that the accuracy estimates of NN and SVM binary classifiers cannot distinguish. This contradicts a modern belief in bioinformatics that SVM outperforms other predictors.
- Full Text:
- Date Issued: 2009
Public discourses on choice of termination of pregnancy in a rural area of the Eastern Cape Province in South Africa
- Authors: Sigcau, Nomakhosi
- Date: 2009
- Subjects: Abortion -- South Africa -- Eastern Cape Abortion -- Public opinion Abortion -- Moral and ethical aspects Abortion -- Social aspects Abortion -- Psychological aspects Discourse analysis -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3055 , http://hdl.handle.net/10962/d1002564
- Description: A period of ten years has elapsed since the Choice on Termination of Pregnancy Act came into effect. Little has been done in South Africa to investigate public discourses concerning termination of pregnancy since the implementation of the Act. The social context and the quality of available support systems determine the outcome of the women’s feelings after the abortion. Knowledge about the social context is important, as it will help to understand the complexities and nuances of abortion. The aim of the research is to explore public discourses on Choice on Termination of Pregnancy (CTOP), and the potential implications of these discourses on the use of the CTOP service. The sample consisted of 23 black isiXhosa-speaking participants from the rural area of the Eastern Cape Province in South Africa. Four focus groups coming from different age groups (between the ages 18 and 52) with both men and women participated in the study. Fictitious vignettes that tap into two different scenarios regarding abortion based on women’s stories were used. Discourses that emerged from people’s text are explained, described and interpreted through a discourse analysis. Since the study was interested in public discourses it led to the discovery of 17 interpretative repertoires as follows: social stigma, abortion equated to murder, degradation of society, pregnancy as an irresponsible act, conditional acceptance, TOP in the context of marriage, future potentiality invested in the foetus, dehumanizing foetus into a clot, shared decision making responsibility, gender dynamics interpretative repertoire, negative post abortion consequences, the scolding versus the supportive nurse interpretative repertoire, alternatives interpretative repertoire, rights versus no responsibility interpretative repertoire, more knowledge needed, male and female or generational differentiation repertoire, and the positive effects repertoire. Abortion is opposed on religious and cultural grounds. TOP has been legalized in South Africa but with this a debate and conflicting views have arisen. These variations in people’s discourses may limit access to TOP for women who need the service.
- Full Text:
- Date Issued: 2009
- Authors: Sigcau, Nomakhosi
- Date: 2009
- Subjects: Abortion -- South Africa -- Eastern Cape Abortion -- Public opinion Abortion -- Moral and ethical aspects Abortion -- Social aspects Abortion -- Psychological aspects Discourse analysis -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3055 , http://hdl.handle.net/10962/d1002564
- Description: A period of ten years has elapsed since the Choice on Termination of Pregnancy Act came into effect. Little has been done in South Africa to investigate public discourses concerning termination of pregnancy since the implementation of the Act. The social context and the quality of available support systems determine the outcome of the women’s feelings after the abortion. Knowledge about the social context is important, as it will help to understand the complexities and nuances of abortion. The aim of the research is to explore public discourses on Choice on Termination of Pregnancy (CTOP), and the potential implications of these discourses on the use of the CTOP service. The sample consisted of 23 black isiXhosa-speaking participants from the rural area of the Eastern Cape Province in South Africa. Four focus groups coming from different age groups (between the ages 18 and 52) with both men and women participated in the study. Fictitious vignettes that tap into two different scenarios regarding abortion based on women’s stories were used. Discourses that emerged from people’s text are explained, described and interpreted through a discourse analysis. Since the study was interested in public discourses it led to the discovery of 17 interpretative repertoires as follows: social stigma, abortion equated to murder, degradation of society, pregnancy as an irresponsible act, conditional acceptance, TOP in the context of marriage, future potentiality invested in the foetus, dehumanizing foetus into a clot, shared decision making responsibility, gender dynamics interpretative repertoire, negative post abortion consequences, the scolding versus the supportive nurse interpretative repertoire, alternatives interpretative repertoire, rights versus no responsibility interpretative repertoire, more knowledge needed, male and female or generational differentiation repertoire, and the positive effects repertoire. Abortion is opposed on religious and cultural grounds. TOP has been legalized in South Africa but with this a debate and conflicting views have arisen. These variations in people’s discourses may limit access to TOP for women who need the service.
- Full Text:
- Date Issued: 2009
Purification and characterization of fructosyltransferase for the synthesis of short-chain fructo-oligosaccharides and investigation into thier anti-carcinogenic properties
- Authors: Nemukula, Aluwani
- Date: 2009
- Subjects: Oligosaccharides , Polygalacturonase , Aspergillus , Fructose , Inulin , Cancer -- Prevention , Cancer -- Research , Carcinogens , High performance liquid chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3927 , http://hdl.handle.net/10962/d1003986 , Oligosaccharides , Polygalacturonase , Aspergillus , Fructose , Inulin , Cancer -- Prevention , Cancer -- Research , Carcinogens , High performance liquid chromatography
- Description: There is a growing attention in the synthesis of fructo-oligosaccharides (FOS) due to their excellent bio-functional and health-promoting properties. The current production processes are limited to chemical hydrolysis reactions of plant extracts, which are often associated with several drawbacks. In this study, fructosyltransferase (FTase) and polygalacturonase (PGase) activities, present in a commercial enzyme preparation (Pectinex® Ultra SP-L) sourced from Aspergillus aculeatus, have been separated and fully purified by anion-exchange and sizeexclusion chromatography. The FTase possesses fructosyl transfer activity for FOS synthesis and the PGase has pectin hydrolytic activity. Fructosyltransferase is a single-band protein with a molecular weight of 85 kDa, whereas PGase is a distinct protein of 40 kDa. The temperature and pH optima of FTase were 60 ºC and 6.0, with a half-life of 8 h; while that for PGase were 40 ºC and 6.0, respectively. FTase was slightly inhibited in the presence of Ni²⁺, Mg²⁺ and urea; but PGase was more susceptible to divalent ions such as Ca²⁺, Mg²⁺ and Mn²⁺. The kinetic parameters (Km and Vmax) of FTase for the hydrolysis of β-(2→1) linkages from sucrose were 752.3 mM and 120.5 μmol.min⁻¹.mL⁻¹, respectively; whereas the same parameters for pectin hydrolysis by PGase were 13.0 mg.mL⁻¹ and 263 μmol.min-1.mL⁻¹, respectively. The purified FTase was able to transfer fructosyl residues from sucrose, synthesizing the corresponding chains of FOS. PGase was relatively stable at 40 ºC (t½ > 3 h), depolymerizing the pectin backbone while releasing the inulins from within the chicory roots. Analysis of various mixtures of FOS by mass spectrometry, HPLC and ¹H-NMR was undertaken. Results indicated that MS with electrospray ionization and ¹H-NMR are capable of providing relative quantitative data of the FOS present in the mixtures. The pharmaceutical effects of various sc-FOS (0.5%, v/v) and SCFA (0.3%, v/v) on certain bacterial enzymes (β-glucuronidase, urease and β-glucosidase) associated with the formation of carcinogens were also studied. These enzyme activities were not directly influenced by the sc-FOS, but were found to be remarkably decreased by SCFA, pointing toward the prebiotic effect of FOS in intestinal microflora modulation.
- Full Text:
- Date Issued: 2009
- Authors: Nemukula, Aluwani
- Date: 2009
- Subjects: Oligosaccharides , Polygalacturonase , Aspergillus , Fructose , Inulin , Cancer -- Prevention , Cancer -- Research , Carcinogens , High performance liquid chromatography
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3927 , http://hdl.handle.net/10962/d1003986 , Oligosaccharides , Polygalacturonase , Aspergillus , Fructose , Inulin , Cancer -- Prevention , Cancer -- Research , Carcinogens , High performance liquid chromatography
- Description: There is a growing attention in the synthesis of fructo-oligosaccharides (FOS) due to their excellent bio-functional and health-promoting properties. The current production processes are limited to chemical hydrolysis reactions of plant extracts, which are often associated with several drawbacks. In this study, fructosyltransferase (FTase) and polygalacturonase (PGase) activities, present in a commercial enzyme preparation (Pectinex® Ultra SP-L) sourced from Aspergillus aculeatus, have been separated and fully purified by anion-exchange and sizeexclusion chromatography. The FTase possesses fructosyl transfer activity for FOS synthesis and the PGase has pectin hydrolytic activity. Fructosyltransferase is a single-band protein with a molecular weight of 85 kDa, whereas PGase is a distinct protein of 40 kDa. The temperature and pH optima of FTase were 60 ºC and 6.0, with a half-life of 8 h; while that for PGase were 40 ºC and 6.0, respectively. FTase was slightly inhibited in the presence of Ni²⁺, Mg²⁺ and urea; but PGase was more susceptible to divalent ions such as Ca²⁺, Mg²⁺ and Mn²⁺. The kinetic parameters (Km and Vmax) of FTase for the hydrolysis of β-(2→1) linkages from sucrose were 752.3 mM and 120.5 μmol.min⁻¹.mL⁻¹, respectively; whereas the same parameters for pectin hydrolysis by PGase were 13.0 mg.mL⁻¹ and 263 μmol.min-1.mL⁻¹, respectively. The purified FTase was able to transfer fructosyl residues from sucrose, synthesizing the corresponding chains of FOS. PGase was relatively stable at 40 ºC (t½ > 3 h), depolymerizing the pectin backbone while releasing the inulins from within the chicory roots. Analysis of various mixtures of FOS by mass spectrometry, HPLC and ¹H-NMR was undertaken. Results indicated that MS with electrospray ionization and ¹H-NMR are capable of providing relative quantitative data of the FOS present in the mixtures. The pharmaceutical effects of various sc-FOS (0.5%, v/v) and SCFA (0.3%, v/v) on certain bacterial enzymes (β-glucuronidase, urease and β-glucosidase) associated with the formation of carcinogens were also studied. These enzyme activities were not directly influenced by the sc-FOS, but were found to be remarkably decreased by SCFA, pointing toward the prebiotic effect of FOS in intestinal microflora modulation.
- Full Text:
- Date Issued: 2009
Racism and law : implementing the right to equality in selected South African equality courts
- Authors: Krüger, Rósaan
- Date: 2009
- Subjects: South Africa Promotion of Equality and Prevention of Unfair Discrimination Act, 2000 , Equality -- South Africa , Discrimination -- Law and legislation -- South Africa , Racism -- Law and legislation -- South Africa , Apartheid -- Law and legislation -- South Africa , Constitutional law -- South Africa , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3677 , http://hdl.handle.net/10962/d1003192 , South Africa Promotion of Equality and Prevention of Unfair Discrimination Act, 2000 , Equality -- South Africa , Discrimination -- Law and legislation -- South Africa , Racism -- Law and legislation -- South Africa , Apartheid -- Law and legislation -- South Africa , Constitutional law -- South Africa , South Africa -- Politics and government -- 1994-
- Description: Racism has informed South African society since colonial times. Racist beliefs found expression in the laws of colonial and apartheid South Africa and shaped both state and society. The constitutional state that South Africa has become since 1994, is based on the values of ‘human dignity’, ‘the achievement of equality’ and ‘nonracialism’, among others. Law formed the basis of the racist state prior to 1994, and now law has a fundamental role to play in the transformation of the state and society in an egalitarian direction by addressing socio-economic inequalities on the one hand, and by changing patterns of behaviour based on racist beliefs forged in the past, on the other. This thesis examines one of the legal instruments that is intended to contribute to transformation in the latter sense, namely the Promotion of Equality and Prevention of Unfair Discrimination Act 4 of 2000 (the Equality Act), with specific reference to the issue of racism. The provisions of this Act and the framework for its operation against the background of South Africa’s racist past, and within the broader framework of international and constitutional law, are examined. These two legal frameworks are analysed for the purpose of determining the standards set by international and constitutional law regarding racial equality in order to determine whether the Equality Act measures up. This thesis also incorporates an analysis of the practical application of the provisions of the Equality Act to complaints of racism in selected equality courts. The theoretical analysis of the Act’s provisions and their application in the equality courts point to various problematic formulations and obstacles which negatively affect the application of the provisions and thus hamper social change. The thesis concludes with recommendations for refining the Act’s provisions and its application.
- Full Text:
- Date Issued: 2009
- Authors: Krüger, Rósaan
- Date: 2009
- Subjects: South Africa Promotion of Equality and Prevention of Unfair Discrimination Act, 2000 , Equality -- South Africa , Discrimination -- Law and legislation -- South Africa , Racism -- Law and legislation -- South Africa , Apartheid -- Law and legislation -- South Africa , Constitutional law -- South Africa , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3677 , http://hdl.handle.net/10962/d1003192 , South Africa Promotion of Equality and Prevention of Unfair Discrimination Act, 2000 , Equality -- South Africa , Discrimination -- Law and legislation -- South Africa , Racism -- Law and legislation -- South Africa , Apartheid -- Law and legislation -- South Africa , Constitutional law -- South Africa , South Africa -- Politics and government -- 1994-
- Description: Racism has informed South African society since colonial times. Racist beliefs found expression in the laws of colonial and apartheid South Africa and shaped both state and society. The constitutional state that South Africa has become since 1994, is based on the values of ‘human dignity’, ‘the achievement of equality’ and ‘nonracialism’, among others. Law formed the basis of the racist state prior to 1994, and now law has a fundamental role to play in the transformation of the state and society in an egalitarian direction by addressing socio-economic inequalities on the one hand, and by changing patterns of behaviour based on racist beliefs forged in the past, on the other. This thesis examines one of the legal instruments that is intended to contribute to transformation in the latter sense, namely the Promotion of Equality and Prevention of Unfair Discrimination Act 4 of 2000 (the Equality Act), with specific reference to the issue of racism. The provisions of this Act and the framework for its operation against the background of South Africa’s racist past, and within the broader framework of international and constitutional law, are examined. These two legal frameworks are analysed for the purpose of determining the standards set by international and constitutional law regarding racial equality in order to determine whether the Equality Act measures up. This thesis also incorporates an analysis of the practical application of the provisions of the Equality Act to complaints of racism in selected equality courts. The theoretical analysis of the Act’s provisions and their application in the equality courts point to various problematic formulations and obstacles which negatively affect the application of the provisions and thus hamper social change. The thesis concludes with recommendations for refining the Act’s provisions and its application.
- Full Text:
- Date Issued: 2009
Recontextualising issues in the 'NISTCOL" environmental education curriculum module for Primary Diploma by Distance Learning in Zambia
- Authors: Moose, John
- Date: 2009
- Subjects: Environmental education -- Zambia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1722 , http://hdl.handle.net/10962/d1003605
- Description: This study investigated the recontextualising of the NISTCOL environmental education curriculum module for the Primary Teachers’ Diploma by Distance Learning (PTDDL) in Zambia. It focused on three case sites, the NISTCOL EE curriculum module for PTDDL and the University of Zambia, the National In-Service Teacher’s College (NISTCOL) and four basic schools: chalimbana, Bimbe, Chongwe and Silver Rest. The study looked at teacher professional development in environmental education in Zambia. The aims and goals were to investigate the NISTCOL EE curriculum and identifying issues that were associated with lecturers in the recontextualising process and further examine what issues were associated with curriculum recontextualisation in Zambian schools. For the conceptual constructs, the research drew on Bernstein’s (1990) framework of pedagogic discourse, it traced how the pedagogic discourse was de-located from the field of production and re-located into the pedagogic practice of each stated case above. It further examined the continuities, discontinuities and changes in the official environmental discourse as it was recontextualised. The study particularly focused on Bernstein’s conceptual constructs of selective appropriation and ideological transformation. In each case the Bernstein framework is used to analyze the process to identify recontextualising issues influencing pedagogical practice in the Zambian schools and college. The study revealed that each case under focus was unique but through examining the environmental discourse and pedagogical discourse in each case recontextalising issues were identified. Each case was influenced by different factors, such as lack of policy synergy, lack of EE vision at national level in Zambia, experience and knowledge, ideologies and emphasis, and depth of engagement. These factors provided me with a deeper insight into the curriculum recontextualising processes in Zambian schools.
- Full Text:
- Date Issued: 2009
- Authors: Moose, John
- Date: 2009
- Subjects: Environmental education -- Zambia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1722 , http://hdl.handle.net/10962/d1003605
- Description: This study investigated the recontextualising of the NISTCOL environmental education curriculum module for the Primary Teachers’ Diploma by Distance Learning (PTDDL) in Zambia. It focused on three case sites, the NISTCOL EE curriculum module for PTDDL and the University of Zambia, the National In-Service Teacher’s College (NISTCOL) and four basic schools: chalimbana, Bimbe, Chongwe and Silver Rest. The study looked at teacher professional development in environmental education in Zambia. The aims and goals were to investigate the NISTCOL EE curriculum and identifying issues that were associated with lecturers in the recontextualising process and further examine what issues were associated with curriculum recontextualisation in Zambian schools. For the conceptual constructs, the research drew on Bernstein’s (1990) framework of pedagogic discourse, it traced how the pedagogic discourse was de-located from the field of production and re-located into the pedagogic practice of each stated case above. It further examined the continuities, discontinuities and changes in the official environmental discourse as it was recontextualised. The study particularly focused on Bernstein’s conceptual constructs of selective appropriation and ideological transformation. In each case the Bernstein framework is used to analyze the process to identify recontextualising issues influencing pedagogical practice in the Zambian schools and college. The study revealed that each case under focus was unique but through examining the environmental discourse and pedagogical discourse in each case recontextalising issues were identified. Each case was influenced by different factors, such as lack of policy synergy, lack of EE vision at national level in Zambia, experience and knowledge, ideologies and emphasis, and depth of engagement. These factors provided me with a deeper insight into the curriculum recontextualising processes in Zambian schools.
- Full Text:
- Date Issued: 2009
Redress : debates informing exhibitions and acquisitions in selected South African public art galleries (1990-1994)
- Authors: Cook, Shashi Chailey
- Date: 2009
- Subjects: South African National Gallery Exhibitions Durban Art Gallery Exhibitions Joahnnesburg Art Gallery Exhibitions Art -- South Africa -- Exhibitions Art, South African Exhibitions South Africa History Exhibitions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2399 , http://hdl.handle.net/10962/d1002195
- Description: This thesis centres on the debates informing the progress of three public art galleries in South Africa between 1990 and 1994. This was a period of great change in the country, spanning from the unbanning of left-wing political parties and Nelson Mandela’s release from prison, to the first democratic elections which resulted in his inauguration as President of South Africa. The study focuses specifically on the Johannesburg Art Gallery, the South African National Gallery, and the Durban Art Gallery, delineating the events and exhibitions held, the programmes initiated, and the artists represented by these galleries during this post-apartheid/pre-democracy phase of the country’s history. The debates relevant to these galleries linked to those prevalent in the arts, museology, and politics at the time. Many contemporary South African artists called attention to apartheid oppression and human rights abuses during the 1980s. After 1990, with these pressures alleviating, there was a stage of uncertainty as to the role, responsibility, and focus of visual art in a post-‘struggle’ context, however there was also an unprecedented upswing in interest and investment in it. On a practical level, the administration of the arts was being re-evaluated and contested by both independent and politically-aligned arts groups. Public art museums and sponsored art competitions and exhibitions made increasing efforts to be ‘representative’ of South Africans of all races, cultures, creeds, sexes and genders. The many conferences, committees, and conventions created during this transitional era focused on the creation of policies that would assist in nation-building; historical and cultural redress and regeneration; and the education and representation of previously disadvantaged groups. This coincided with a revolution in museological discourses internationally, from the theorization of a museum as a place of commemoration and conservation, to a forum for discussion and revision between both academic and non-academic communities. With the sharing of the process of constructing history and knowledge, came the challenging dynamics involved in the representation of identity and history. In all of these groups - the arts, museology, and South African politics - the predominant issue seemed to be a negotiation between the bid to open up control to more parties, and the reluctance of some parties to relinquish control. While the emphasis is on significant changes that were implemented in the transitional period, the study locates the changes at the Johannesburg Art Gallery, the South African National Gallery and the Durban Art Gallery within their historical, geographical, and socio-political context. Various artists working in these locations during this era are also discussed, as the changes in their status, and the progressions in their subject matter, materials, and concerns are interesting to examine more nuanced definitions of the ‘political’, probing the politics of identity, sexuality, gender, race, geography, and belief systems. Some artists also focused specifically on post-apartheid preoccupations with territory, trauma, conflict, memory and freedom. This kind of artwork was assiduously acquired during the early ‘90s by public art galleries, whose exhibitions and collecting focus and policies were undergoing considerable revision and redress. This thesis examines these changes in light of their socio-political contexts, as well as in light of shifting national and international imperatives and conceptions of museums and museum practice.
- Full Text:
- Date Issued: 2009
- Authors: Cook, Shashi Chailey
- Date: 2009
- Subjects: South African National Gallery Exhibitions Durban Art Gallery Exhibitions Joahnnesburg Art Gallery Exhibitions Art -- South Africa -- Exhibitions Art, South African Exhibitions South Africa History Exhibitions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2399 , http://hdl.handle.net/10962/d1002195
- Description: This thesis centres on the debates informing the progress of three public art galleries in South Africa between 1990 and 1994. This was a period of great change in the country, spanning from the unbanning of left-wing political parties and Nelson Mandela’s release from prison, to the first democratic elections which resulted in his inauguration as President of South Africa. The study focuses specifically on the Johannesburg Art Gallery, the South African National Gallery, and the Durban Art Gallery, delineating the events and exhibitions held, the programmes initiated, and the artists represented by these galleries during this post-apartheid/pre-democracy phase of the country’s history. The debates relevant to these galleries linked to those prevalent in the arts, museology, and politics at the time. Many contemporary South African artists called attention to apartheid oppression and human rights abuses during the 1980s. After 1990, with these pressures alleviating, there was a stage of uncertainty as to the role, responsibility, and focus of visual art in a post-‘struggle’ context, however there was also an unprecedented upswing in interest and investment in it. On a practical level, the administration of the arts was being re-evaluated and contested by both independent and politically-aligned arts groups. Public art museums and sponsored art competitions and exhibitions made increasing efforts to be ‘representative’ of South Africans of all races, cultures, creeds, sexes and genders. The many conferences, committees, and conventions created during this transitional era focused on the creation of policies that would assist in nation-building; historical and cultural redress and regeneration; and the education and representation of previously disadvantaged groups. This coincided with a revolution in museological discourses internationally, from the theorization of a museum as a place of commemoration and conservation, to a forum for discussion and revision between both academic and non-academic communities. With the sharing of the process of constructing history and knowledge, came the challenging dynamics involved in the representation of identity and history. In all of these groups - the arts, museology, and South African politics - the predominant issue seemed to be a negotiation between the bid to open up control to more parties, and the reluctance of some parties to relinquish control. While the emphasis is on significant changes that were implemented in the transitional period, the study locates the changes at the Johannesburg Art Gallery, the South African National Gallery and the Durban Art Gallery within their historical, geographical, and socio-political context. Various artists working in these locations during this era are also discussed, as the changes in their status, and the progressions in their subject matter, materials, and concerns are interesting to examine more nuanced definitions of the ‘political’, probing the politics of identity, sexuality, gender, race, geography, and belief systems. Some artists also focused specifically on post-apartheid preoccupations with territory, trauma, conflict, memory and freedom. This kind of artwork was assiduously acquired during the early ‘90s by public art galleries, whose exhibitions and collecting focus and policies were undergoing considerable revision and redress. This thesis examines these changes in light of their socio-political contexts, as well as in light of shifting national and international imperatives and conceptions of museums and museum practice.
- Full Text:
- Date Issued: 2009